Battery-Only Wiring for PNP Fuzz

[Ginsly]

I'm close to trying some Ge circuits, and even after looking at various threads I'm a little confused about how to set these circuits up properly power-wise.

I have no problem with battery-only operation, and I think I'll set up any Ge or Ge/Si hybrids this way to be safe. I'm not quite sure how to wire the battery snap so that the Input Jack still acts as a "battery off" switch when nothing is inserted. In a normal NPN circuit I usually attach the battery's black lead to the input jack's ring and red to the middle lug of a switched DC jack. Do I simply reverse them?

I assume any Ge/PNP PedalPCB projects or vero diagrams are already going to be set up the correct way when it comes to the direction of polarized caps and power.

I mention this because I've seen a lot of discussion about simply "flipping polarized caps and your power's + and -". It sounds like this (or a voltage inverter IC) are utilized so that one can use a standard negative ground power supply - I'm not really concerned with that, and I feel like leaving it Positive Ground is the safest bet, especially for battery-only operation. RG Kean's warning about motorboating and noise makes me think it's not worth it.

Again, wouldn't things be set up the correct way already on a pcb or vero diagram meant for PNP transistors? I'm not sure which situation merits these on-the-fly changes - maybe if you were using PNP transistors in a pcb/vero diagram normally meant for NPNs? I think this'll click with just a little clarification - I'd really appreciate it! I certainly don't want to fry anything...

Project-wise I have a Dizzy Elk lined up, and I'd like to try this too:

 

[jwin615]

In "positive ground" circuits, i.e. grd/-9v, the + terminal on the battery is ground.
So, if a schematic/layout indicates, -9v, that's the black therminal, assuming whomever made it designated it properly.
Another thing to keep in mind with these is the actual grounding of jacks. Probably best to leave the circuit isolated and just ground jacksnto the enclosure. I'm not certain on that aspect. Maybe someone else can chime in.

 

[Ginsly]

@jwin615 thanks man! Yeah, this is really confusing me...

In that Peppermint vero, for example - looks like I could just attach the +/red lead from the battery to "Ground+" on the board and the -/black battery lead to "-9v", but this way the Input Jack doesn't act as a battery shutoff - so how would I prevent the battery from draining, even when a cable isn't inserted?

I guess the same question applies for a normal, NPN PedalPCB build too - if I don't include a DC jack, how would I wire a snap to a PPCB board so that the battery doesn't constantly drain?

 

[Harry Klippton]

You need a switched jack. Run the + connection from the snap to the switched lug, and the other lug to ground

 

[Ginsly]

You need a switched jack. Run the + connection from the snap to the switched lug, and the other lug to ground

Ah. Ok - so a stereo jack would never cut it when going battery-only, huh? I'd always need a switched (stereo?) jack, whether dealing with PNP or NPN?

Thanks for the pic, that definitely helps. I can see the red snap lead going to the input jack's switched lug, but where are you connecting black to ground?

I can also see that nothing connects to the - power pad at the top of the pcb, but I can't tell if something is connected to + up there... This info will help when it comes to wiring up something like that Peppermint Vero - I'm still pretty confused about what would connect to the -9v pad and Ground+ pad...

Much, much appreciated - things are falling into place but some basic knowledge is still lacking!

I JUST ordered from Tayda, so I'll have to find some switched jacks elsewhere - looks like there are many kinds. If you have a favorite, a link would be awesome!

 

[Ginsly]

Still pretty lost, unfortunately...

1) In a normal NPN circuit, if I was omitting the DC Jack and going battery only I could:

- Attach the Black/Ground battery snap lead to the Stereo Input Jack's Ring.
- Attach the Red/Positive battery snap lead to the "+" pad on the PCB, Vero, or 3pdt Breakout Board.

Correct? It seems like this would still prevent the battery from draining... @Harry Klippton you mentioned a Switched Jack, but I found a thread where @Robert mentions a Stereo Jack for these purposes (which would be great because I actually have those!). Not sure if I can use either one or if it HAS to be Switched.

2) In a PNP circuit where I use no inverters, keep it positive ground, and go battery-only for power:

- Attach the RED battery snap to the Stereo Input Jack's Ring this time.
- Attach the BLACK battery snap to the "+" pad on the PCB, Vero, or 3pdt Breakout Board.

I have the feeling this might not be correct. I'd REALLY appreciate some clarification about this, I can't seem to find a definitive answer...

 

[coltonius]

Here’s a Peppermint gut shot:




The red lead of the battery snap (usually referred to as positive, or + ) connects to the Ring of the input jack. The Sleeve then connects to the circuit’s ground.

IMPORTANT: For the purpose of this PNP circuit, just pretend (+) is negative and (-) is positive. Should you decide to add a DC jack, don’t daisy chain with a typical (-) negative circuit.

 

[Ginsly]

Here’s a Peppermint gut shot:

View attachment 70444


The red lead of the battery snap (usually referred to as positive, or + ) connects to the Ring of the input jack. The Sleeve then connects to the circuit’s ground.

IMPORTANT: For the purpose of this PNP circuit, just pretend (+) is negative and (-) is positive. Should you decide to add a DC jack, don’t daisy chain with a typical (-) negative circuit.

Thank you so much for that! So where would I connect the Black/ground lead from the battery snap? To the “+” voltage area on the pcb where I would normally attach the positive lug of a DC Jack? I assume I can then leave the corresponding “-“ power pad open if I’m connecting the jack sleeves to ground via a 3pdt pcb?

It’s odd - in that photo there seems to be two “9v+” pads next to each other… why is that?

I really appreciate you taking the time to chime in!

 

[Harry Klippton]

If you weren't using the battery disconnect via the input jack, you'd just hook your battery leads backwards. Start there with conceptualizing it. So if red is your + on the battery (make sure you check it) and black is - then connect red to the ground pad and black to the +9v on your board. Instead of connecting both directly, you want to send you "ground," which is red in this case, to the ring lug of your input jack, and the sleeve of your input jack is already gonna go to ground. Boom done. If you can't get it from there, you're on your own

 

[Feral Feline]

Here’s a Peppermint gut shot:

View attachment 70444


The red lead of the battery snap (usually referred to as positive, or + ) connects to the Ring of the input jack. The Sleeve then connects to the circuit’s ground.

IMPORTANT: For the purpose of this PNP circuit, just pretend (+) is negative and (-) is positive. Should you decide to add a DC jack, don’t daisy chain with a typical (-) negative circuit.

Thanks for the gutshot!

Found the following, "PeppermintPCBtraced_zps463040d8", on my HD after DLing your gutshot:




No recollection of where I found that layout or the veracity of it.

 

[Ginsly]

If you weren't using the battery disconnect via the input jack, you'd just hook your battery leads backwards. Start there with conceptualizing it. So if red is your + on the battery (make sure you check it) and black is - then connect red to the ground pad and black to the +9v on your board. Instead of connecting both directly, you want to send you "ground," which is red in this case, to the ring lug of your input jack, and the sleeve of your input jack is already gonna go to ground. Boom done. If you can't get it from there, you're on your own

Got it, 100%. Thanks Harry - that makes perfect sense! So it looks like I can indeed use stereo input jacks for this, as they are a kind of switching jack. Sorry folks, I’m ten weeks in! Takes time for things to click...

 

[Mcknib]

Just a general comment on how I remember it, positive ground can get confusing

I generally just think of it as ground is a zero voltage reference and its either positive or negative but it's always 0v

Ground still connects to ground regardless of its polarity

That helps me connect everything up correctly although now and again I still get confused but that's just an age thing